Abstract: The inventive intermediate fixing element (1) is embodied in one piece by injection moulding and comprises a plate (2) which is substentially flat and comprises a first or top surface and a second or lower surface, at least one anchoring element (6), for example in the form of a herringbone or a tree produced directly by the top surface moulding and hooks (7) which are produced directly by the lower surface moulding and whose shape, sizes and thermoplastic material are selected in such a way that said hooks, after being shaped in a mould and extracted therefrom, substentially recover the initial shape thereof, wherein said hooks are sufficiently flexible in order to be bent during extraction from the mould.